Pneumatic, hydraulic and electric hand-held power tools are used in thousands of different work areas. Tools which translate the rotation of a rotary driving motor to a reciprocating lateral movement, for sawing, filing and polishing for example, often give rise to considerable vibration, which can be transmitted to the hand and arm of the person using the tool.
Prolonged use of vibrating tools can cause changes in tendons, muscles, bones and joints, and can affect the nervous system. Collectively, these effects are known as Hand-Arm Vibration Syndrome (HAVS). The symptoms of VWF are aggravated when the hands are exposed to cold.
Workers affected by HAVS commonly report: attacks of whitening (blanching) of one or more fingers when exposed to cold, tingling and loss of sensation in the fingers, loss of light touch, pain and cold sensations between periodic white finger attacks, and loss of grip strength, as well as bone cysts in fingers and wrists in some cases.
The development of HAVS is gradual and increases in severity over time. It may take a few months to several years for the symptoms of HAVS to become noticeable. As scientific confirmation of these delayed effects has been forthcoming, attempts to avoid these debilitating effects have been given increasing emphasis over the past few decades.
In addition to the use of anti-vibration gloves, limitations on maximum hours of exposure to vibration and use of sharper cutting tools, stricter requirements have been placed on vibration levels generated by hand-held power tools, measured in frequency weighted acceleration (m/s2). The standard developed by the American Conference of Government Industrial Hygienists (ACGIH) prescribes a maximum of 4 m/s2 for 8 hour use. The European Directive 2002/44/EC mandates an upper absolute limit of 5 m/s2 for an 8 hour period.
The hand-held power tool industry has been under significant pressure for some time now to develop tools which can generate sufficient reciprocating linear active force for sawing and filing for example without the reactive forces being transmitted to the hand holding the tool.